This invention relates to a liquid spray apparatus for dispensing liquid droplets of constant droplet size, comprising a liquid container and a spray plate with a drive located in a spray head.
In order to spray chemical substances such as herbicides, insecticides and the like for agricultural application, there are known liquid spray apparatus having spray nozzles, such as are described in the German patent application Nos. 24 52 750 or 25 41 213. A serious drawback of these conventional spray nozzle apparatus consists in that the droplet size varies greatly. Small droplets evaporate rapidly or are carried away by the wind, so that they are ineffective. Droplets which are too large cause an unnecessarily high consumption of liquid and therefore a low efficiency.
A better efficiency is attained by apparatus having rotating discs such as have been described in German patent application Nos. 25 35 084 or 31 45 109. The liquid is directed on to the disc on which it is carried outwardly and from which it is flung off due to centrifual forces. By regulating the speed and by providing gear-tooth means on the periphery of the discs, the droplet size can be determined relatively exactly, whereby a highly uniform distribution of the liquid is guaranteed. However, the drive by means of transport wheels, on the one hand, or an electric motor, on the other hand, are of disadvantage. These apparatus are, indeed, relatively heavy and their operational life is limited because of a battery being used. Furthermore, these apparatus are subject to corrosion and their long term maintenance is expensive, because the batteries must be replaced periodically.
Due to their electrical drive means, the known apparatus are not suitable for use, e.g., in developing countries, in spite of the fact that there is a vast need for liquid spray apparatus particularly in these areas. Even a drive comprising transport wheels is not suited for use in those regions where, due to their topography, portable apparatus are required.